De or het vader-overste?

The correct Dutch article is:

de vader-overste

Rule Words ending in -te: usually de. See the rule

How to use vader-overste

the vader-overstede vader-overste
this vader-overstedeze vader-overste
that vader-overstedie vader-overste
our vader-oversteonze vader-overste
your vader-overstejouw vader-overste
every vader-oversteelke vader-overste
which vader-overste?welke vader-overste?
a big vader-overste / the big vader-oversteeen grote vader-overste, de grote vader-overste